Out of the tap it is around 9 at my place and will drop to 6 - 6.5 within a day. I buffer with sodium bicarbonate (baking soda.) The kh is 0 so without adding some kind of buffer i've seen the ph crash to 4 within a day. Learned my lesson the first week I moved to Minneapolis from Bloomington. I buffer the water to 7 kh before doing a water change. I can make RO/DI as well but typically just use tap.